3) Can you turn Jim into Frank?
Like producers of a makeover show, researchers found a group of elderly couch potatoes, measured their brain power, exercised them, and then reexamined their brain power. The researchers consistently found that all kinds of mental abilities began to come back online—after as little as four months of aerobic exercise. A different study looked at school-age children. Children jogged for 30 minutes two or three times a week. After 12 weeks, their cognitive performance had improved significantly compared with prejogging levels. When the exercise program was withdrawn, the scores plummeted back to their preexperiment levels. Scientists had found a direct link. Within limits, it does appear that exercise can turn Jim into Frank, or at least turn Jim into a sharper version of himself.
As the effects of exercise on cognition became increasingly clear, scientists asked the question dearest to the couch-potato cohort:
4) What type of exercise must you do, and how much?
After years of investigating aging populations, researchers’ answer to the question of how much is not much. If all you do is walk several times a week, your brain will benefit. Even couch potatoes who fidget show increased benefit over those who do not fidget. The body seems to be clamoring to get back to its active Serengeti roots. Any nod toward this evolutionary history, be it ever so small, is met with a cognitive war whoop. In the laboratory, the gold standard appears to be aerobic exercise, 30 minutes at a clip, two or three times a week. Add a strengthening regimen and you get even more cognitive benefit. Individual results vary, of course, and exercising too intensely, to exhaustion, can hurt cognition. One should consult a physician before embarking on an exercise program. The data merely point to the fact that one should embark. Exercise, as millions of years traipsing around the globe tell us, is good for the brain. Just how good took everyone by surprise, as they delved into the next question.
5) Can exercise treat dementia or depression?
Given the robust effect of exercise on typical cognitive performance, researchers wanted to know if it would have an effect on atypical performance. What about diseases such as age-related dementia and its more thoroughly investigated cousin, Alzheimer’s disease? What about affective (mood) disorders such as depression? Researchers looked at both prevention and intervention. With experiments reproduced all over the world, enrolling thousands of people, often studied for decades, the results are clear. Your lifetime risk for general dementia is literally cut in half if you participate in physical activity. Aerobic exercise seems to be the key. With Alzheimer’s, the effect is even greater: Such exercise reduces your odds of getting the disease by more than 60 percent.
How much exercise? Once again, a little goes a long way. The researchers showed you have to participate in some form of exercise just twice a week to get the benefit. Bump it up to a 20-minute walk each day, and you can cut your risk of having a stroke—one of the leading causes of mental disability in the elderly—by 57 percent.
Dr. Steven Blair, the man most responsible for stimulating this line of inquiry, did not start his career wanting to be a scientist. He wanted to be an athletics coach. Surely he was inspired by his own football coach in high school, Gene Bissell. Bissell once forfeited a winning game. He realized after the game that an official had missed a call, and he insisted that his team be penalized. Young Steven never forgot the incident. But Bissell encouraged Blair to continue his interest in research, and Blair went on to write a seminal paper on fitness and mortality. The study stands as a landmark example of how to do work with rigor and integrity in this field. His analysis inspired other investigators. What about using exercise not only as prevention, they asked, but as intervention, to treat mental disorders such as depression and anxiety? That turned out to be a good line of questioning.
A growing body of work now suggests that physical activity can powerfully affect the course of both diseases. We think it’s because exercise regulates the release of most of the biochemicals associated with maintaining mental health. In one experiment on depression, rigorous exercise was substituted for antidepressant medication. Even when compared to medicated controls, the treatment outcomes were astonishingly successful. For both depression and anxiety, exercise is beneficial immediately and over the long term. It is equally effective for men and women. The longer the person exercises, the greater the effect. Although exercise is not a substitute for psychiatric treatment (which usually involves therapy along with medication), the role of exercise on mood is so pronounced that many psychiatrists prescribe physical activity as well. It is especially helpful in severe cases and for older people.
In asking what else exercise can do, researchers looked beyond our oldest members to our youngest.
6) Does exercise help kids do better in school?
The number of studies in children is downright microscopic. Still, the data point in a familiar direction. Physically fit children identify visual stimuli much faster than sedentary ones. They appear to concentrate better. Brain-activation studies show that children and adolescents who are fit allocate more cognitive resources to a task and do so for longer periods of time. “Kids pay better attention to their subjects when they’ve been active,” Dr. Antronette Yancey said in an interview with NPR. “Kids are less likely to be disruptive in terms of their classroom behavior when they’re active. Kids feel better about themselves, have higher self-esteem, less depression, less anxiety. All of those things can impair academic performance and attentiveness.”
Of course, many ingredients make up academic performance. Finding out what those components are—and then which are most important for improving performance—is difficult. But these preliminary findings hint that exercise may be one key ingredient.
An exercise in road building
Why exercise works so well in the brain, at a molecular level, can be illustrated by competitive food eaters—or, less charitably, professional pigs. The crest of the International Federation of Competitive Eating proudly displays the motto In Voro Veritas—literally, “In Gorging, Truth.” Like any sporting organization, competitive food eaters have their heroes. The reigning gluttony god is Takeru “Tsunami” Kobayashi. He is the recipient of many eating awards, including the vegetarian dumpling competition (83 dumplings downed in eight minutes), the roasted pork bun competition (100 in 12 minutes), and the hamburger competition (97 in eight minutes). Kobayashi also is a world champion hot-dog eater. One of his few losses was to a 1,089-pound Kodiak bear. In a 2003 Fox-televised special called Man vs. Beast, the mighty Kobayashi consumed only 31 bunless dogs compared with the ursine’s 50, all in about 2½ minutes. The Tsunami would not accept defeat. In 2012, Kobayashi ate 60 bunless dogs in that amount of time. But my point isn’t about speed.
Like the Tsunami’s, the brain’s appetite for energy is enormous. The brain gobbles up 20 percent of the body’s energy, even though it’s only about 2 percent of the body’s weight. When the brain is fully working, it uses more energy per unit of tissue weight than a fully exercising quadricep. In fact, the human brain cannot simultaneously activate more than 2 percent of its neurons at any one time. More than this, and the brain’s energy supply becomes so quickly exhausted that you will faint.
That energy supply is glucose, a type of sugar that is one of the body’s favorite resources. After all of those hot dogs slide down the Tsunami’s throat, his stomach’s acid and his wormy intestines tear the food apart (not getting much help from the teeth, in his case) and reconfigure it into glucose. Glucose and other metabolic products are absorbed into the bloodstream via the small intestines. The nutrients travel to all parts of the body, where they are deposited into cells, which make up the body’s various tissues. The cells seize the sweet stuff like sharks in a feeding frenzy. Cellular chemicals greedily tear apart the molecular structure of glucose to extract its sugary energy.
This energy extraction is so violent
